How hot should Hydraulic cylinder get?

I split about 2 rick of wood today on my log splitter. Logs were all huge and pump was in low volume/high pressure mode most of the time. Cylinder was very warm to touch. Not so hot you could not hold your hand to it, but very warm. I would guess about 140 degrees. Is this to hot? I have a 10 gallon tank and have never felt it this warm before. Usually, I split when it is much cooler outside. It was near 80 degrees today.

Re: How hot should Hydraulic cylinder get?

140°F is good. In an industrial setting, provided you have no water or aeration issues, the oil would last about 10,000 hours. Every 10 degrees above 140 cuts the life in half, so obviously cooler is better. For off-road equipment it is not unusual to run oil temps of 180-200 during very hard usage.

Re: How hot should Hydraulic cylinder get?

go touch a cylinder on an excavator thats been running for 12hrs. i bet its above 140*. go touch something like a milling head that you can put on a skidsteer. i bet you cant even disconnect the hoses without gloves on

Re: How hot should Hydraulic cylinder get?

ISZ, is that 10 degrees F or C ? I ask because with capacitors (electronic components) the rule of thumb is every 10 degrees C rise halves the life of the part. This rule semi-applies to semiconductor junctions (transistors) too. In my youth, I build an amplifier where the final transistor with no heat sink ran so hot it would boil spit. It lasted 6 months, if at the right temp it would last 40+ years.

Re: How hot should Hydraulic cylinder get?

140 is fine. A lot of units run oil coolers thru the engine rad tanks to cool the oil to 180 F. While most people think 140 deg is HOT water temp, in reality very few people can hold their hands in 140 deg, even after getting aclimatized. 120 deg water feels very hot, 110 is normal hand wash temp....
Our bearing supplier used to tell us to heat them in boiling water if they were tight when putting on the shaft. (back before they were all sealed)

Re: How hot should Hydraulic cylinder get?

Originally Posted by eepete

ISZ, is that 10 degrees F or C ? I ask because with capacitors (electronic components) the rule of thumb is every 10 degrees C rise halves the life of the part. This rule semi-applies to semiconductor junctions (transistors) too. In my youth, I build an amplifier where the final transistor with no heat sink ran so hot it would boil spit. It lasted 6 months, if at the right temp it would last 40+ years.

Anyway, just curious 10 degrees F or C ?

Pete

ISZ related to 140....so that must be "F"....so he wouldn't mix in Celsius then.....

Re: How hot should Hydraulic cylinder get?

I stated everything in F, as most people here are from the states. My job would be easier if everyone just switched to C though.

In my job as a test engineer for several off-road OEMs I have often tested the cooling capacity of machines and they are almost always insufficient for long term high HP use. They fact of the matter is the average machine is designed for the 80-90th percentile user for 7-10 years. If they were made better they would cost too much and nobody would buy them (unless you put a CAT sticker on the side. )

As far as the oil temp goes, it is tough to find good information but I have been collecting bit and pieces for years. The 140°F number is the general consensus from a dozen different sources for mineral oil based, generally industrial usage, hydraulic oils. Part of the problem is that "hydraulic oil" is really a complex chemical cocktail, and the additives amounts vary between suppliers and change as new/cheaper additives become available. Many blenders will not even give you a straight answer - all they care about is copying blends and making the quick buck. They let the Big Boys do the research. As the temperature affects the recommended oil change interval: at 165°F you need to change the oil twice as often compared to 140°F. Thee times as often at 180°F as compared to 140°F.

Re: How hot should Hydraulic cylinder get?

I run my log splitter, which is a 30 ton HF unit with too small a tank, until I start smelling the ATF I use for fluid. At that point the cylinder is pretty hot to the touch. By then I'm ready for a break anyway
Maybe I'll remember next time I'm splitting to put the IR temp gun to it...I'm more worried about pump, hose, and seal durability than I am about cooking the fluid.

Re: How hot should Hydraulic cylinder get?

Sycko, Your situation sounds very similar to my old log splitter, which had an 11gpm pump, 5 gal tank, and a 4" cylinder. It got noticeably hotter in warm weather.

I built a new larger splitter recently, it runs much cooler.

The two types of heat created in splitters are the heat of compression and frictional heat.
The heat of compression is the "work" being done by the cylinder.
Frictional heat is created by the friction encountered in the plumbing system.
A well plumbed system won't create as much frictional heat, a system with a lot of elbows, restrictions and undersized hoses will create more frictional heat.

When I designed the new splitter, I gave attention to the plumbing, always opting for the least amount of restriction, which means a little cooler running.
Heat of compression is caused by the cylinder doing work at a given pressure. I used a larger pump and larger diameter cylinder, so it doesn't have to work as hard, thus, the larger diameter cylinder can split a given log with less overall pressure (less heat created) than a smaller cylinder at higher pressures.

My initial thought is that a 30 ton unit shouldn't be running in High pressure stage that much, unelss you are splitting a very tough wood species.

If your oil filter is old, I'd advise changing it. They typically start bypassing at about 15 or 16psi, but that is enough to cause back-pressure that will also cause more frictional heating, even when no work is being down. The other thing to look at is the plumbing itself. if there are any restrictions, like undersized fittings, small diameter hoses, reducers, etc. you can replace them to make it a more free flowing system.

Example: a ran a short 3/4" hose into my filter housing, but then stepped it up to 1" from the Out port of the filter housing, going into the tank. The idea is trying to reduce backpressure and give it unrestricted flow back to the tank.

As people stated above, a hdyraulic system will run XX degrees above ambient temp, if you split when it's 80 degrees F outside, but normally are splitting when it's 40F outside, the oil could run up to another 40F warmer, just due to the rise in ambient temps.

All in all, my old splitter was the same as yours, got pretty warm, but not so hot you couldn't touch it. Mine was also an HF unit.
I used it for a long long time with no issues. It just ran fairly warm to the touch.